Chemistry Exam Past Questions and Answers | JAMB, WAEC and NECO

Chemistry is the study of the substances that make up matter. It looks at their properties, how they react with each other, and how these reactions can create new substances.

• Question 281: Reduction of nitroalkanes, nitrites and amides is a route for the preparation of Options:
  A) amines
  B) alkenes
  C) polymers
  D) detergents
  Show Answer
  The correct answer is A .
• Question 282: A metallic ion X²⁺ with an inert gas structure contains 18 electrons. How many protons are there in this ion? Options:
  A) 20
  B) 18
  C) 16
  D) 2
  Show Answer
  The correct answer is A .
• Question 283: The property used in the industrial preparation of nitrogen and oxygen from air is Options:
  A) rate of diffusion
  B) density
  C) boiling point
  D) solubility
  Show Answer
  The correct answer is C .
• Question 284: An oxidation state of or in K2CrO7 Options:
  A) 7
  B) 6
  C) 5
  D) 4
  Show Answer
  The correct answer is B .
• Question 285: The mathematical expression of PH is Options:
  A) log ₁₀[OH^-]
  B) log ₁₀1/[H ₃ O⁺]
  C) log ₁₀[H ₃ O⁺]
  D) log ₁₀1/[OH ^-]
  Show Answer
  The correct answer is B .
• Question 286: The most important use of hydrogen is in the Options:
  A) manufacture of ammonia
  B) manufacture of methyl alcohol
  C) manufacture of ethyl alcohol
  D) hydrogenation of oils
  Show Answer
  The correct answer is A .
• Question 287: Which of these properties gives a solid its definite shape? Options:
  A) strong intermolecular attraction
  B) high melting point
  C) high boiling point
  D) weak intermolecular attraction
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  The correct answer is A .
• Question 288:

  

  Choose the correct answer from the options above.

  When Fehling's solution is added to two isomeric carbonyl compounds X and Y with the molecular formula C ₅H ₁₀O, compound X gives a red precipitate while Y does not react. It can be inferred that X is

  Options:
  A) A
  B) B
  C) C
  D) D
  Show Answer
  The correct answer is B .
• Question 289:

  The densities of two gases, X and Y, are 0.5 g dm^-3 and 2.0 dm^-3 respectively.

  What is the rate of diffusion of X relative to Y?

  Options:
  A) 0.1
  B) 0.5
  C) 2.0
  D) 4.0
  Show Answer
  The correct answer is C .
• Question 290: The soil around a battery manufacturing factory is likely to contain a high concentration of? Options:
  A) Ca²⁺ salts
  B) Pb²⁺ salts
  C) Mg²⁺ salts
  D) Al³⁺ salts
  Show Answer
  The correct answer is B .